But that doesn't answer my question. I don't know how to gift things to people nor do I understand what's in the boxes. I figured out you need to pay real money for them though? Which I won't do.
You can gift the items by doing a trade with a person. You do that by right clicking on the person and initiating a trade. It's a rather safe process where one sees the items being traded and then requires confirmation on both ends before transaction is complete.
Items are randomly generated by using a specific box key on the crate. Each key costs on average about $2.50. You can either buy them new from Steam, or just buy them for a couple cents cheaper on the marketplace through users.